Which coordinate system should I use to collect GPS data?

“Is this the standard configuration ( WGS 84 LLA ) in iCMTGIS pro? Will it transfer back and forth in different coordinates? Or should I collect data also in NC State Plane since shapefiles are NC SP?”

Internally our software stores location data in WGS 84(1674)/ITRF08.

The options under Setup – Coordinate system is for you to select the coordinate system for displaying the position data.

Many people use the WGS 84(1674)/ITRF08 system on the iCMTGIS PRO because they are familiar with it.

You can set the iCMTGIS PRO to NC State Plane to collect GPS data if you wish to see the coordinates displayed in that system.

The important thing to remember is that when you are combining data (such as by importing Shapefiles), you must make sure that they are in the same coordinate system. You cannot add apples to oranges and expect to get a sum that represents the total number of oranges. In many cases you don’t have the option to change the coordinate system of the Shapefiles at their source. Therefore, our iCMTGIS PRO and PC software provides the ability to switch to the coordinate system used by the Shaepfiles to be imported.

Some people also use geo-referenced images in .tif format. Here again, you will need to find out what coordinate system the .tif file refers to before trying to load it into our software.

For people who make use of data from a RTK network, the Datum must be set to match that used by the RTK base station.

Is there a way to add the RTK solution type in the built-in attributes of iCMTGIS PRO?

“I am a land surveyor and having the solution type for each collected point is something very important (actually it is mandatory with my professional association) since this information is related to the precision/accuracy.”

The app provides setting for PDOP Mask, 3D only, RMS Limit and DGPS.

PDOP, 2D_3D, C_or_U, and 2DRMS values are available as built-in Attributes.

You can set the PDOP Mask, 3D only, the RMS limit, and mark DGPS (meaning DGPS only) to ensure that the data meets the quality requirement.

If you mark the DGPS check box, that means the app will only record data when it is DGPS. This is much better than logging the data and recording the GPS/DGPS status then later checking the data to see if it meets the requirement.

Similarly, setting the RMS limit and also have the app record the 2D RMS values as built-in Attributes will show your association the quality of your data.

As the solution type for each collected point when collecting data with a GPS RTK receiver/software combination is important for your professional association, we are working on adding it to the built-in Attributes list for the next release of iCMTGIS PRO. We will also add the RMS value to the built-in Attribute list so that it may be recorded along with the location data.